Most standard tools have long tapered or cylindrical shanks which insert into tool shank bores in a tool holder. The tool is removed from the holder by pulling it axially from the tool holder until the back end of the shank clears the forward face of the holder. In most instances, manipulation of the machine spindle or work piece is necessary in order to provide clearance for changing the tools.
Tool holders are known which permit the tool to be inserted and removed in a direction perpendicular to the axis of the tool holder. For instance, the patent to Egli, U.S. Pat. No. 4,176,991, discloses a hinged tool holder adapter which mounts to the machine tool. The tool holder adapter includes a tool shank bore which is open on one side. The tool is provided with an adapter extension insertable into the tool shank bore in a direction normal to the axis of the spindle. A clamping gate is hinged along the side of the tool holder so that it may be opened in door-like fashion to permit insertion and removal of the tool.